Production of alkyl aromatic hydrocarbons utilizing a common reagent as aromatic extractant and alkylation catalyst



May 19, 1953 c. B. I lNN ETAL 2,639,303

PRODUCTION oF ALKYL AROMATIC HYDRocARBoNs UTILIZING A COMMON REAGENT As AROMATIC EXTRACTANT AND' ALKYLATION cATALYsT Filed Dec. so, 1949 Ffac zozza or] Patented May 19,- 1.953

This invention rltsitn aikyitioii @recess ecinms; and @Qmlglexty Qi" many' Qlfii wiiic'li liasasits ultimate obieetivetiie produc-tion employing' am; aromatic; hticiroolaiboil. Charent@- of aryl; 'hydioearbeiis .partarl'y ot the beheerstools: partzciilsriy sismioarit; sind, @paient in mie. series. More speeieallmtneiiiveiition eontrie ailksiiittioiiefarometie hydroealfbonm atl,- ceriis combination process invorving' the vex- 5 themen these ieeticzis. Likewise oserei@ 1n seen; tfaletion ofafomatienydrocarhons from apetme sroes'ses as the mtodiiotion of phenoiie 'come leem fraction containing the. samein even. smani pounds starting imm, the corresponding; eroine is coneeiitazti'nsutiiizing a selective solvent vtiii'oh hydxoearbon. in the. oxidation@ @miti ilo hmmprlefen'entiaiiy extracts said amnistie iiycltocer-V terriens; te form the earboxizlis; aioid, ketoiiio etici; boris: iii parimne. components' also 1g'ts'exitA in 10 'eld'ehxe derivatives there@ as Well; as numerous said ffaciion aindwhicfi is. alsoc'apahe 0I Cata 1 er" other JLOQQSSQS 0f diverse. dlaliai'iiei-, y lylzing' 'the coiidensatoii of the aromatic iiydo's It is engohect of this intention to movido en carbon.; contained in the extiact phase recovered euliqmial process Qi. the ultimate PIQQuGiQXl. frojiii'tlie eiitr'aeton stage with arioiencvhydio- I o iarliieitie Ingerman/ion. eikylgatejs. Another' obs cer,imiifsiibseinenitrit` admixed 'therewith 15 jest of 'the invention is to devise o. method of' ne'efthe 'meist fetorsdeteiiiziing the; eoiriutilizing; inexpensive, amnistie hydizoeaibonssilit-Y- metci'ai utilityoi a pnqees's involving en er me-tic. if tattili-ing, "get'ls'oleum fratolis as 'al siarltiiig' hydroeern :is one of the rieaetint materiels is teiten 'in the production or 'aillsitiatyi hyiiizoserftfi 20st of `the in'til -aiotnati Iydrcaib'ciii. Wheis utilizing e.y 'given 'aroiiitiefelirg'i-ng stetkv 20s-gent products thereiifoni. I Stili another objective: ineiir'tieuiar poeess and intfeduciiigptne seme y .of the invention is the menuiattliie of en ellsizb inte the process iiotv in a relatively iam/fe form, -r-jfogvaxzyi hydrocarbon e combination proeess in.- te e'st'f statr1g`-i't'er'ils is' fic'iueritly pire,- towing exirctn. and," resulting Connelitraifsm hititivedue to the high 'cost ef' mire aromatic f or thea-:ometto hydidcaxhoti @chinees elixir-Leohyd bons andcoeentretesjtheieof,euch tiit 25 f ceptor in the mimetica of seid.; alkyleritl hydro,- the 'process becemes commercial-ly inoperative `for` f lc'alrbon and condensation of; the aromatic: hydros prctieal' purposes Fu'rthermre, in uieiiiy incarbon thus exitila'ted with am, Qlenic, hydra: stances, due to the essential mechanism 'ofthe carbon alkyleting agent in 'the presente of, en reitetiii 'er iiiliefetproperties of the reactants, eliitflztt Ionl catalyst whioh also serves in 'the the 'reaction p'm'c'eeds and practical yields are 30 ..-c apa ctyvof selective solvent in the preceding exs obtained only when a relativeit7 concentrated are traction steigeL thus' afmeting said extratoii and meti hydioc'abo chagtig stok is 'employed iii said alkylatin in at QQIitiiiilQli princess Wthglliit the process. As an illustrative example f trie f intermediate sepai'ationo the solvent sxtreetant latter fet'o operative in typical yprocesses lemfrqmtiie aromatic liydioearbon reeovered in the pitting-an arematie'nydrocarton @berging steels, 4.1 -.extraation, The present Process timides im the yield of elkylete obtained in the 'endeiis'atien effective means of eceompiishiiig these and other of toluene 'with dodeeyiene inthe presence oio'sui- -obiotsas horeinsiter appear in the further fui-ie aeid esalkylation 'eatalys't a'rid'the quentity 'description 0f 'the present invention. of catalyst co'nsumed'to form undesirable slud'ge- 1 In one 9 1 its embodiments the. present milenlike products isdirectiyproportionalto theco'ntion klitio-tes to e eombinetioii sol-vent extraction eeiitationof toluene in the a'romatieconteiitrate and alkyialtion process which comprises sommet ehargedto the elkyltion reaction. The fomit-s ing 'a mixture or aromatic and.' paireiiinie hydms ing Teble I indieates this reltionshp: jai'bos with sii extraistive 'Solvent for said em- TABLE-I -liietio hydrocarbon comprsineiiqud liyirossn #197: ma www? Cqtwlmg Wam@ ha leest one or the groep ,consisting of the silver.

wel@ @if `allettante and emulation catalyst emv l gold, platinum, palladium mercury tluortie's.

www1? N l eyanides, and rlitrdcs, sspaetixig 'an extrai'ot phase leomprising `soieLsQlveiit sind said arometi hydrate-thon 2mg thereaifter sometime said exs Itratt :phase with en oleiliiie `h:ritiroteilten .et

lityietioit -reaoton s :cmdiiiriis Toluene cenentmtm, weight Y `Percent `more speei embodiment olf the invention ggg; gg; 55 oogieerns' e protest 15er the profitietien e my 9557 dod'eeyihenzoid "hydroeatrbon which empi-ists t M4 i e @stesisnt est' m fr-tetten 'm tbm unetevm 'when este@ the particularly toi' tile msnuieetur'e or; deter.

gen fluoride and'a salt selected from the group consisting of the silver and mercury uori'des,

cyanides and nitrdes containing from about 1% to about by weight of said salt at a temperature and under extraction conditionsto selectively dissolve in said hydrogen uorilde-salt extractant the aromatic hydrocarbons'contained in said fraction, separating a resulting extract phase, contacting said extract phase with a mixture of olenic hydrocarbons containing dodecylene at a temperature of fromabout -30 to`abou t 30 C. and at other reaction conditions to eiec't condensation of said aromatic hydrocarbons with said oleiinic hydrocarbons, separating a hydrocarbon alkylate product from the alkylation reaction mixture, distilling said hydrocarbon product and separating the fraction therefrom comprising hydrocarbons corresponding in boiling point to said dodecylbenzenoid hydrocarbon.

Other embodiments of the invention relating` to the use of a charging stock in the extraction stage containing a low concentration of aromatic hydrocarbons therein, such as a straigh-trun gasoline distillate which contains a relatively high proportion of the aromatic hydrocarbon desired for the ultimate alkylate product. The use of such a charging stock thus provides an economical source of the required aromatic hydrocarbon and enables the production of 4.the alkylate in optimum yields without the interference of other hydrocarbons such as parafns and naphthenes which act as diluents of the aromatic hydrocarbon and which would otherwise reduce the yield of alkylate if present inthe alkylation reaction in admixture with the aromatic hydrocarbon. Another factor of importance in an alkylation reaction employing aromatic hydrocarbon concentrates in which paraflins and naphthenes are also present is the contamination of the catalyst with by-product hydrocarbons. The latter combine and react with the catalyst to form sludgelike products therewith from which the catalyst is subsequently recovered with considerable diniculty necessitating additional processing stages and contaminate the alkylate product with paraf- 4 ability to'y catalyze :the a'lkylation reaction. Furthermorasinc'e merely 'one reagent is "used for both the extraction and alkylation stages, no

contamination of the reactants in the system results by virtue of inclusion of the solvent extractant inthe lallrylation stage. From the standpoint --of equipment requirements and operating concentration stage.

procedure', the 'provision in the present process for a single reagent which serves in the dual ca- 'pacity of an extractive solvent of the aromatic y-reactantand acatalyst for accomplishing the condensation of'lthel aromatic and olenic reactants eliminates at least one regeneration or re- Thus, merely one regenerating stage is required instead of the usual two when v employing one reagent to effect solvent extraction and another, different reagent to act as jalkylation catalyst, each of which would require reconcentration, purification, etc.. for rej-V cycletok the individual stages of theproc'ess Suitable aromatic hydrocarbon-containing mixtures forutiliaation as the initial charging stockv in the present extraction stage of ythe combination extraction-allrylation process may be ,derived from any source, provided the non-aromatic components in the -mixture do; 'not interfere with the extraction or' alkylationf operations andare non-reactive with Athe hydrogen fluoride-heavy metal salt extractive solvent.

The preferred aromatic hydrocarbons vutilizable in lthe present process are'the .mono-nuclearor benzenoid hydrocarbons selected. from the group consisting vof benzene itself and y theInor 1o a .r 1c l dialkyl derivativesinwhich the alkyl groups contain fewer than three carbon atoms per group, such as toluene, dimethylbenzene, methyl-ethyl'- benzene, and 'diethylbenzene the former being particularly preferred for subsequent alkylation with'long chain olens containing from about 9 to about 18 carbon atoms per olefin molecule for' the production of the alkylate intermediate in the.

manufacture of detergents'of the alkylaryl sul;v fonate type.l Mono-nuclear or benzenoid hydrocarbons are preferred in the present process` because 'of the .generally greater' easeof alkylation and for the additional reason that the alkylate products are more readily separated from the alkylation reaction mixture in the subsequent stage ofthe process. Further preference is accorded the benzenoid aromatic-containing hydrocarbon charging stocks for the reason that more selective choice of the aromatic hydrocarbon may iin and cycloparaflin alkylates thus removing olefin alkylating agent from the reaction mixture and reducing the yield of the desired aromatic alkylate from a given charge of olefin in the process. This .difficulty is substantially eliminated in the presentprocess by concentrating the de sired aromatic hydrocarbon in the alkylation catalyst and separating the samefrom contaminating parafns and cycloparaflins Yintroduced as a mixture with the aromatic hydrocarbon-containing charge stock. The present opbe obtained by merely charging a distillate fraction boiling within a range in which the desired aromatic hydrocarbon boils. Thus, a straight run gasoline distillate containing from about 5 toabout 15%. by Weight of benzenoid aromatic hydrocarbons in adrnxture with paraffin, and cycloparafhn hydrocarbons may be fracticnally distilled to separate a distillatel fraction containing a predominant proportion of the particular desired .aromatic hydrocarbon. A fraction, -for example, boiling normally at from about' 70. to about C. at atmospheric pressure will conta-in aromatic hydrocarbons, the predominant proportion of which is benzene. Likewise, a fraction boilingy from about 100 to about 125 C. will contain toluene as the principal' aromatic hydrocarbon,componentpthereof In a similar fashion, other fractions may be separated to provide a charging stock in which the primary aromatic hydrocarbonbomponent is a particular species stage of from about 0.1 pound of aromatic hydrocarbon. per pound of catalyst to two pounds of aromatic hydrocarbon per pound of catalyst. In order that this preferred ratio of aromatic hydrocarbon to catalyst willfprovide a sufficient volume of extractive solvent in the extraction stage of the process (thesolvent containing dissolved aromatic hydrocarbons being transferred directly to the alkylation stage), the extractive solvent may be recycled continuously in the extraction stage to remove substantially all of the aromatic hydrocarbon from the hydrocarbon mixture charged to the extraction stage and yet maintain the aromatic hydrocarbon to catalyst ratio within theabove specified` desired proportions, for effecting the alkylation reaction. The preferred method of operating the extraction procedure involves a system of countercurrent extraction in which the solvent having the greatest density is charged into the top of a vertical column and allowed to flow downwardly, preferably as small, liquid droplets or over a suitable packing material as the aromatic hydrocarboncontaining mixture is charged into the bottom of the column and thereafter permitting the hy. drocarbon charging stock to percolate upwardly through the extraction column and out of a suitable vent located at the top of the column. The extraction apparatus may consist of several towers in series and the extractive solvent and/ or aromatic hydrocarbon-containing charging stock may be recycled yto effect substantially complete removal of the aromatic component from the latter mixture. The extraction stage of the process is desirably conducted at temperatures and pressures which will maintain the hydrogen uoride in substantially liquid phase during the process. For this purpose, temperatures of from about 10 to about 0 aresuitable at atmospheric pressure and up to about 30 C. for mildly superatmospheric pressures` The extraction-alkylation process is further described and illustrated in the following diagram which represents a typical process flow and one of the alternative methods of operation. It is to be noted that Ithe diagram is illustrative of merely one procedure for effecting the present process and other methods consistent with the process will be readily apparentto those skilled in the art. Referring tothe diagram, an aromatic hydrocarbon containing mixture, such as a straight run gasoline distillate is charged into extraction column I through line 2 containing valve 3 and allowed to percolate upwardly through extraction column I which is desirably packed with a suitable contacting material resistant to the action of hydrogen fluoride, such as copper rivets, stainless steel rings, or bubble plates and risers which distribute the liquid phases therein to obtain maximum Contact oetween the extract-ant and hydrocarbon mixture introduced into the column. As the hydrocarbon mixture is charged into column I, the extractant, comprising a liquid hydrogen fluorideheavy metal salt solution is introduced into the ltop of the column through line 4 containing valve 5 and may alternatively comprise a mixture of fresh extractant and recycle extractive solvent obtained as hereinafter described. Since the extractive solvent is the more dense phase in the column, it tends to percolate downwardly through the rising column of hydrocarbon mixture in countercurrent relation thereto. The less dense rainate phase from which the aromatic hydrocarbons have been substantially extracted is re- 8, moved from the top of the column through line 6 and recycled to the bottom of the column or diverted to a subsequent extraction column in series with extraction column I when the railinate contains residual aromatic hydrocarbons incompletely extracted in column I. An extract phase comprising liquid hydrogen fluoride and heavy metal salt containing dissolved aromatic hydrocarbons removed during the extraction is withdrawn from column I through line 'I and directed to alkylation reactor 8 wherein it is thoroughly mixed with an alkylating agent, such as an olenic hydrocarbon introduced into reactor 8 through line 9 containing valve I0 which controls the iiow of alkylating agent into reactor 8 and consequently the aromatic to .alkylating agent ratio during the alkylation reaction. The extract phase or effluent stream from column I containing the hydrogen fluoride and heavy metal salt in solution therewith serves as alkylation catalyst in reactor 8, promoting the condensation of the aromatic hydrocarbon and alkylating agent therein. In order to obtain intimate admixing of the alkylating agent, aromatic hydrocarbon and alkylation catalyst, reactor 8 is desirably equipped with a suitable stirring means such as motor driven stir II. Following completion of the alkylation reaction, usually within a period of from about l@ to about 2 hours in duration, the mixture of hydrocarbons, alkylating agent and catalyst is removed either continuously or intermittently from reactor 8 through line I2 and valve I3 and discharged into settling vessel I4 wherein phase separation occurs while the reaction mixture is allowed to stand quiescent in vessel I4. In some instances, particularly when the alkylating agent is a relatively short chain olen or olefin-acting compound, such that the resulting alkylate retains its primarily aromatic characteristics, the HF- heavy metal salt mixture retains the alkylate in solution. In such instances, the catalyst phase is separated from the alkylate by fractionation to recover a vaporized hydrogen fluoride distillate and the alkylate and heavy metal salt componente separately. Another method for effecting separation of the catalyst phase from the hydrocarbon alkylate phase when such separation does not occur by stratification, comprises adding waiter to the alkylation reaction mixture until phase separation occurs and thereafter decanting the resulting insoluble alkylate phase from the lower aqueous catalyst phase. In the majority of cases, however, and particularly when the alkylating agent contains a long chain alkyl group, the alkylate is predominantly parain in character and separates from the hydrogen fluoride-heavy metal salt catalyst solution. Upon stratification of the alkylate and catalyst phases, the former is removed from settler I4 through line I5 containing valve I6 and diverted, if desired, to a fractional distillation column, not illustrated, for separating the hydrocarbons contained therein into fractions of the desired boiling range. The lower catalyst phase stratifying in settling vessel I 4 is removed therefrom through line I1 containing valve I8 and in the preferred method of operation is directly recycled to the extraction column by joining line I'I with solvent supply line 4 leading into column I wherein the catalyst serves the purpose of extractive solvent to provide the aromatic hydrocarbon concentrate by extraction, as aforementioned.

The present process is further illustrated with respect to 'certain specific embodiments thereof accesos Y :"An. 'alkylate of benzene containing anl alkyl '--grouplof from. about l2 to about 15 carbon. atoms per alkyl groupmaybe` produced inV accordance with the present procedure in the following run.

A Trinidad 4straight-frun gasoline fraction boilingupl tof about 100 C. and containing .approximately 7% by volume ofbenzene is contacted in a V'erticalsilver-lined `extraction column. with an extractant consisting` of a solution of silver fluoride 'inliquid 98.5%-ihydrogennuoridc at, approximately C.` Theextraction.colnmncontains silverplated Copper Raschig rings to enhance the liquid phase contact between the straight gasoline-i *fraction and hydrogen fluoride-silver fluoride extractant. The extractionis-"erectedcountercurrently by introducing the extractant intothie top of the. packed column and permitting the straight-run gasoline fraction to percolateupwardly against a dewnwardrfiowing `Istreamer. the vextractant. Approximately equivolumetric proportions ofA straight-run gasoline and extractant are charged into the extraction column.l The extractionA is operated con- .tinouslwandanextract effluent .containing approximately 5% by weight ci belnfsen'eE .is ,removed from the column and diverted to an alkylation reactor in which the alkylaticn stage of the present process is effected as hereinafter described. The raiiinate phase which is removed from the top of the extraction column, is substantially free of aromatic hydrocarbons.

The extract phase removed from the extraction column and comprising a hydrogen fluoride-silver fluoride solution of aromatic hydrocarbons consisting predominantly of benzene is charged into a continuous now, stirred alkylation pressure autoclave and raised to a temperature of about 10 C. at 20 pounds per square inch pressure as a mixture of olenic hydrocarbons consisting predominantly of dodecylene is charged into the autoclave. The oleiinic hydrocarbons were prepared in a previous process by polymerizing propyiene over a solid phosphoric acid catalyst (a calcined composite of pyro-phosphoric acid and lzieselguhr) at a temperature of 350 C. and 120 p. s. i., the propylene polymerization products being fractionated to separate a distillate fraction boiling from about 170 C. to about 225 C. containing principally dodecylene and smaller proportions of pentadecylene. The olefins are added continuously to the hydrogen fluoride, silver fluoride, and benzene mixture in an amount to provide a hydrocarbon mixture containing approximately an equimolar proportion of benzene to propylene polymers on the basis that the olelns have an average approximate molecular weight of 182. The mixture of benzene, olens and alkylation catalyst is retained in the alkylation reactor at approximately 10 C. and 20 p. s. i. pressure for a residence period of one-half hour and is then discharged into a settling tank wherein a hydrocarbon product phase is permitted to separate from a resulting hydrogen fluoride-silver fluoride catalyst phase. The hydrocarbon phase is removed to a fractional distillation column to separate a dodecylbenzene fraction boiling from about 270 to about 325 C. and the remaining unconverted hydrocarbons recovered as separate fractions are recycled to the alkylation reactor. The lower phase recovered from the settling ves- 1.0 sel comprising; the Asilver fluoride liquidihydrogen uorlde solution. is returned .to .the .benzene rextraction column where it is mixed with sufficient fresh makeeupextractantto operate the gasoline extraction stage` ofthe process. The dodecylbenzene and. pentadecylbenzene alkylates separated vby fractional distillation of thexalkylate product represent a combined yield oi approximately based uponthe benzene present .in

therextract' phase.

. K Ewample' JI.

A Trinidad straight-run gasoline fractionboiling from about' i60 to about 135 C. and containing approximately 28% by volume of toluene is charged into the bottom of anr extraction column and allow'ed to percolate upwardly through a 'stream' o extract'aiit consisting of a solution-of 6 %by Weight orrnercur'ic iluoridey dissolved in hydrogen iluoride of- 985% purity which flows' downwardlyand out of the bottonil of the column in countercurrent relationship tothe-gasoline charging-stock. The extractant is charged to the coliunn at a rate of approximately three volumes per volume of straight-run gasoline fraction, sufficienttoprovidean effluent stream containing from about 10 tol about 1'2 Volumes of hydrogen fluoride-mercurio fluoride solution per volume vof .toluene recovered from-'the gasolinedistillate.

The' r'a-in'at'e eiiiuent from the extract column contains less than' 1% by' Volume of toluene-remaining therein on a once-through extraction basis.

The extract effluent from the toluene extraction is continuously mixed with a propylene polymer fraction boiling from about 170 to about 2225o C., comprising a mixture of C12 to C15 olefin polymers, and the resulting mixture allowed to flow through a tubular reactor maintained at a temperature of about 10 C. and at a pressure of 20 pounds per square inch. The respective streams were charged at a rate suiiicient to provide a residence time of the toluene `and dodecylene components in contact with the hydrogen iiuoride-mercuric iluoride solution oi about 45 minutes, 'the reaction mixture being vigorously stirred as the two streams are mixed `and allowed to react. Following the above period of reaction, the alkylation reactor eiiluent is transferred to a settling vessel in which the hydrogen nuoridemercurio iluorlde solution separates from a resulting hydrocarbon product phase as a lower layer which may be withdrawn or decanted and thereafter recycled to the extraction column for reuse therein as extractant. A yield of approximately of a fraction boiling from about 275 to about 345 C. and comprising principally dodecyltoluene is obtained by fractional distillation of the hydrocarbon phase of the alkylation reaction product.

cury luorides, cyanides, .and nitrides, separatingan extractphase comprising said solvent and sa1d aromatic hydrocarbon and thereafter contacting said extract phase containing` said solvent and aromatic hydrocarbon with an oleiinic hydrocarbon at a temperature of from about 36 '11 to about 30 C. and other reaction conditions to alkylate the aromatic hydrocarbon with the olefinic hydrocarbon.

2. The process of claim 1 further characterized in'that said mixture -of aromatic and paraiiinic hydrocarbons is a straight-run gasoline fraction.

3. The process of .claim 1 further characterized in that the aromatic component of said mixture of aromatic and paranic vhydrocarbons is predominantly a benzenoid aromatic hydrocarbon.

4. The process of claim 3 further characterized in that said olenic hydrocarbon contains from about 9 to about 18 carbon atoms per molecule.

5. The process of claim 1 further characterized in that said salt is silver fluoride.

6. The process of claim `1 further characterized in that said extractive solvent contains from about 1 to about 10% by'weight of said salt.

7."A process for the production of a dodecylbenzenoid hydrocarbon which comprises'c'ontacting a straight-run petroleum fraction boiling from about 70 to about 150 C. with a mixture of liquid, substantially anhydrous hydrogen fluoride and a salt selected from the group consisting of the silver and mercury iluorides, cyanides and nitrides containing from about 1% to about 10% by weight of said salt at a temperature and under extraction conditions to selectively dissolve in said hydrogen fluoride-salt extractant the aromatic hydrocarbons containedl in said fraction,

separating a resulting extract phase, contacting said extract phase with a mixture o1' olenic hydrocarbons containing dodecylene at a, temperature of from about -30 to about 30 C. and at other reaction conditions to effect condensation of said aromatic hydrocarbons with said oleflnic hydrocarbons, separating 'a hydrocarbon alkylate product from the alkylation reaction mixture, distilling said hydrocarbon product and separating the fraction therefrom comprising hydrocarbons 'corresponding in boiling point to 'said dodecylbenzenoid hydrocarbons.

8. The process of claim 7 vfurther characterized in that said salt is silver fluoride.

9. The process of claim 7 further characterized in that said salt is mercurio fluoride. Y

vCARL B. LINN.

GEORGE L. HERVERT.

References Cited in the'iile ofl this patent UNITED STATES PATENTS Number Name Date 2,378,762 vFrey June 19, 1945 2,477,382 Lewis July 26, 1949I 2,531,723 Carnelll -1 Nov. 28, 1950 OTHER REFERENCES Ipatieff et al., Jour. of the Am. Chem. Soc., June 1936, pages 919-22. 

1. A COMBINATION SOLVENT EXTRACTION AND ALKYLATION PROCESS WHICH COMPRISES CONTACTING A MIXTURE OF AROMATIC AND PARAFFINIC HYDROCARBONS WITH AN EXTRACTIVE SOLVENT FOR SAID AROMATIC HYDROCARBON COMPRISING LIQUID SUBSSTANTIALLY ANHYDROUS HYDROGEN FLUORIDE CONTAINING DISSOLVED THEREIN A SALT STABLE IN SAID HYDROGEN FLUORIDE AND SELECTED FROM AT LEAST ONE OF THE GROUP CONSISTING, OF THE SILVER, GOLD, PLATINUM, PALLADIUM, AND MERCURY FLUORIDES, CYANIDES, AND NITRIDES, SEPARATING AN EXTRACT PHASE COMPRISING SAID SOLVENT AND SAID AROMATIC HYDROCARBON AND THEREAFTER CONTACTING SAID EXTRACT PHASE CONTAINING SAID SOLVENT AND AROMATIC HYDROCARBON WITH AN OLEFINS HYDROCARBON AT A TEMPERATURE OF FROM ABOUT -30* 